Safety casing head



Jan. 9, 1940. F, w, HILD 2,186,139

SAFETY CASING HEAD Filed Jan. 9, 19s? 3 sheets-sheet 1 zy'w ze l//ifl/ v Jan. 9,1940. F w H|| D 2,186,139

SAFETY CAS ING HEAD Filed Jan. 9, 19:57 s sheets-Sheet 2 92 ov, 7@ 65 4 75 PUMP E f 1,". l 4 71,- 70%/ 7 7? 3J a 654; 7 Z

i u 2 1 5 7 A g d@ x 63 Summa `Ian. 9, 1940.' 9 F. w. HILD 2,186,139

SAFETY CASING HEAD Filed Jan. 9, 1937 3 Sheets-Sheet 3 @a zo; 10g /05 Patented Jan. 9, 1940 UNITED STATES PATENT OFFICE Application January 9,

10 Claims.

My invention relates to casing heads for supporting casings in oil and gas wells, this application being a continuation-in-part of my copending applications Serial No. 733,854, led July 5, 1934, for Expanding seal, and Serial No. 108,777, led Nov. 2, 1936, for Casing heads for pressure drilling. It is an object of the present invention to provide safety casing heads for wells which may be drilled with or withoutmud uid.

Disastrous, costly experiences of the past have demonstrated the serious risk and danger of relying solely upon weighted fluid to control well pressure, hence a control column comprising master valves and mechanical blowout preventers of various types for the axial outlet is practically universal equipment for well drilling. Indeed it is the practice in some fields of high pressure and expensive well jobs to install two and even three master valves and also two blowout preventers in the control column for each well.

But in all cases and in all elds the control column is above the casing heads. So in order to install any of the currently used casing heads, or to secure and seal the casing to the casing head, the control column with its master valves and blowout preventer must be removed; but before this may be done it is essential that there be no pressure at the casing head, and so the well is killed by mud iluid. But the mud may become gas-cut, its specific gravity lessened and its capacity for holding the well pressure be correspondingly diminished.

Thus there is the inconsistency and serious hazard of the well being unprotected by any mechanical shut-oil device, and reliance placed solely upon the mud fluid in the well to control the well pressure during the protracted, critical period' of installing the casing heads and landing and securing the casing. The danger here involved is greater than during the drilling period'because it is not possible to pump mud to the bottom of the hole where it should go to be eiective.

Withdrawal of the drill pipe not only lowers the mud level, but the swab action draws in gas from the pressure formation. Mud or weight material pumped in during the withdrawal, usu- .ally does not go to bottom, but leaves the lower mud fluid in gassy condition and lighter in weight so that the counter pressure of the mud column diminishes. Moreover, when casing'with its end closed inthe customary manner, is being lowered, it displaces the heavier mud fluid at the top, which further reduces the counter pressure.

It is an object of my invention to provide a 1937, Serial No. 119,796

mechanical means for closing the intercasing space between the casing being landed and the next adjacent casing, prior to removal of the drilling control column.

When the natural clays fail to provide mud of sufficient weight, then weight materials such as barites and iron oxides are added. These weight materials in the quantities used per well are quite expensive. My invention has for one of its objects a simple low cost mechanical closure for the intercasing space, which supplements the ordinary mud uid of natural clays so that the costly heavier weight materials will not be needed.

It is an object of the invention to provide a sub-casing head which may be interposed between two casing heads and which will provide a mechanical shut-off below and for the upper of the two.

It is well known that the heavy mud fluid frequently-seals off the productive formation so as to lessen the production and even at times to kill it off permanently. Hence pressure drilling is coming into wide use. But here also, at present, the mud fluid still is relied upon down to the top of the productive horizon; the mud is then replaced by oil and/or gas for circulaing during drilling in. My invention makes relianceupon the mud quite unnecessary.

Another object is to provide a sub-head adapted to be secured to a casing head and having means for effecting seal against the casing prior ,to removal of thewell control column, and prior to securing the casing to the casing head. A y

further object is to provide rthe sub-head with suitable openings for conducting uid from the well. l

Still another object ofthe present invention is to provide in a casing head a packing means which may be urged against a casing by fluid pressure from an external source and which will effect seal by both said pressure and by the well pressure so that in the event of failure or lessening of either pressure, the seal will be maintained.

Still another object is to provide a casing head employing a hollow packer which seals three elements, namely, the casing and twoadjoining casing heads.

Other objects and advantages will be apparent from the following description and the accompanying drawings; p

Figure 1 is an elevational view in part section of the sub-casing head and shows a packer effecting seal against a casing.

Figure 2 is a sectional view on the line 2--2 of Figure 1, and shows the packer relaxed and in retracted position.

Figure 3 is an elevational view in part section of an assembly of casing heads employing tapered slips for securing the upper end of the casing.

Figure 4 is an elevational view in part section of an assembly of my improved casing heads each employing a collar as the terminal end of the casing.

Figures 5 and 6 are reproduced from my aioresaid co-pending application Serial No. 733,854, Figure 5 being a sectional elevation of casing heads employing slips and hollow packers for securing and sealing casings and Figure 6 is a detail of a portion of Figure 5.

Figure 7 is an elevational view in part section of another form of sub-casing head.

Referring to the drawings and particularly to Figures` 1 and 2, the sub-casing head I0 is interposed between and secured uid tight to a lower casing head or landing base I I and an upper casing head I2. The outer casing I3 is secured to the lower casing head II.

The sub-head I comprises the body I4 and the hollow expanding packer I which is contained in an annular recess I6 of the body. A circular opening I1 extends vertically through the body having minimum diameter about the same as the inner diameter of the casing I3, so that any object such as a bit which can v pass through the casing may be passed through the sub-head. The body I4 has lower and upper flanges I8 and I9 respectively which are provided with suitable means such as bolts, tongue, groove and gaskets for fluid tight connections to the casing heads II and I2 respectively. The body I4 has lateral openings 20 and 2| of which the lower one 20 is threaded toreceive a pipe for conducting iluid from the casing head.

Secured into the upper opening 2| is a hollow stem 22 which leads to the interior of the hollow packer I5. A pump 23 may be connected to the stem 22 for inating the packer. Extending downward from the inner facevof the packer I5 is the dependent annular lip 24. When the packer is not inated and is therefore retracted into recess I'B, the well pressure tends tourge the lip 24 against the wall of opening I1 and the remainder of the packer further into the recess I 6. When fluid pressure as by the pump 23 is admitted into the hollow interior of ,the packer I5, the packer is urged radially inward so that the inner face of the packer and its lip effect closure and seal against the casing 25 which extends through the sub-head I0. 'I'he well pressure acting now on the outer surface of the lip 24 forces the lip against the casing. Should the pump pressure fail, the well pressure will hold the lip against the casing. Should the well pressure lessen or stop, the upper portion of the packer will be held against the casing by the pump pressure. 'I'hus the packer eii'ects seal either by external pressure or by well pressure. Manifestly when both pressures are exerted the shut-01T and seal are doubly a.ssured.j

Figure 1 shows the casing 25 heldin the casing head I2 by the tapered slips 26 and. sealed therein by the packer 21 and the retaining nut 28. Plugs 29 close the lateral outlets in the body of the casing headIZ. dicate the sub-head for the next casing head for supporting the next inner casing.

But prior to the insertion of the slips 26 and the packer 21, the numeral 30 may represent the bottom of a well control column comprising the The numeral 30 may in usual master valve and blowout preventer. The casing 25 may then be considered as being lowered through the control column and through the sub-head I0, where the packer I5 may have been expanded against the casing, the lower end of which is closed by a valved oat shoe. Shut-olf and seal below the control column would then be in effect, and if the hole were also then lled with mud, there would be triple insurance against the well blowing out, namely the mud, the subhead I0 and the well control column.

Casing 25 may now be anchored and cemented after which the control column may be disconnected from casing head I2 and lifted uprd. The sub-head I0 and the mud then provide double protective insurance. The casing may then be stretched to desired tension and the slips 26 inserted into the casing head I2 for permanently securing the casing thereto.v The por,u tion of the casing above the casing head is then cut oli and the packer 21 for sealing between the casing and casing head is inserted. Then to the casing head I2 may be secured the next sub head (numeral 30) together with its casing head. The well control column may then be added ready for the next drilling and casing cycle.

Figures 3 and 4 show the equivalent of subhead l0 incorporated in each casing head body. Thus in Figure l3 the casing head 3| has the body 32 which contains in a suitable recess the hollow packer 33. The outermost casing 34 is secured as by welding to the lower portion of the body 32. Above the packer recess the body is taper bored to receive the slip 35 permanently securing the upper end of the next casing 36 to the casing head. Below the packer recess the body 32 has the lateral openings 31 and 38 of which the lower one 31 is threaded to receive the usual vent pipe, and the upper opening 38 contains the stem for the hollow packer 33. The packer and its dependent annular lip 39 are in sealing contact with the casing 36 which is the intermediate casing of this assembly.

The body 32 has lower and upper flanges 40 and 4I respectively. The lower flange rests upon a suitable foundation. The upper ange 4I isgrooved to receive a metallic gasket 42, which prior to the insertion of the slips 35, may have served to render fluid tight connection with the well control column. But as here illustrated, there is seated on the gasket 42, a gland or sealing cap 43 which fits around the intermediate casing 3G and receives a second metallic gasket 44 which seals against the casing.

Seated on the gasket 44 is the casing head 45, the body 46 of which has lower and upper anges 41 and 48 respectively. The lower flange 41 is rmly bolted to the upper flange 4I of casing head 3I and this bolt pressure together with the weight borne by casing head 45 forces the gasket 44 securely into seal against the casing 3B and the sealing cap 43, and also increases the sealing effect of gasket 42. Similarly the casing head 45 has the hollow packer 49, the vent opening 50, the slips 5I, the seal cap 52 and the metallic gaskets 53 and 54. Seated on the upper gasket 54 and'bolted to the casing head at the upper ange 48 may be the well control column or another casing head. The slips 5I permanently secure the inner casing 55 to the casing head 45.

Referring to Figure 4, the outermost casing 56 is welded to the landing base 51. The second casing 58 is threaded into the lower end of casing head 59 which is secured fluid tight to the landing base by suitable bolts. The third casing fil arcane 88 is threaded into a terminal collar 8| which is secured to casing head 59 by the locking ring 82. A lateral threaded opening 83 in the lower part of the casing head ls adapted to receive a pipe for conducting iluid from the casing head. A hollow packer 64 is contained by the casing head in a suitable recess above the opening 63 and below the locking ring 62. The hollow packer has a dependent annular lip and is inl sealing contact with the terminal collar. an upper flange 65 with a groove containing a metallic packing 68. Seated on this packer is the gland or seal cap 61 which surrounds terminal collar 6| and contains the metallic packing 68 for sealing against the collar.

The fourth casing 69 is threaded into terminal collar 18 which is secured to the next casing head 1| by the locking ring 12. The casing head 1| is seated on the packing 68 and bolted to upper flange 65 of casing head 59. The casing head 1| has lateral threaded opening 13, hollow packer 14, seal cap 15 and metallic packings 18 and 11.

'he fth and innermost casing 18 with its terminal collar 19.1's secured to the topmost casing head 88 by locking ring 8|. The topmost casing head is seated on packing 11 of casing head 1| and bolted thereto. Under the locking ring 9| is the gland or seal cap 82 bearing on the metallic packing 83 which is in the upper part of the casing head. The locking ring is bolted to the casing head, the weight of the casing 18 acting through the locking ring and the gland 83 to force the packing 83 into seal against the terminal collar. The casing head 88 has lateral vent opening 84 and hollow packer 85.

Figures 5 and 6 show the casing heads 86, 81, 88 and 89 nesting one into the other for supporting the casings 98, 9|, 92 and 93 respectively on foundation 94. In lieu of threaded joints, tapered slips in the collars grip the casngs and expanding seals provide the fluid tight packing at the joints.

The outermost or surface string of casing 98 is threaded into base plate 86 which rests directli7 on foundation 94. Seated on base plate 88 is casing head 81 which has. the double flanged body 95 from which projects downwardly the pendent tapered slip ring 98. The body has lower ange 81 and an upper ange 98, the space between the iianges permitting bolt heads or nuts for securing to the next casing head 88. The interlange space is bridged at one or more places to form blocks with radial threaded vent holes for receiving 'rent pipes 99.

W'hen lowering the casing 9| into iinal position in casing head 81, the slips |88 are inserted between the slip ring 96 and the casing, and then the portion of casing projecting above the body 95 is cut off. The slips are sufciently below the top of the flange 98 to permit inserting the packina ringr |8| and the expanding seal or packer |82. The packing ring rests on a shoulder in the body 95 into which it is tightly seated. The seal |82 is also well below the top of flange 98 so as to provide a groove for the tongue |83 of casing head 88 which rests upon and nests into casing head 81.

A hole in the packing rini1r |8| receives a check valve |84 which provides controlled passage into hollow packer |82 for fluid under pressure from yc'sing 9|. Also a hole bored radially through upper flange 98 of casing head 81 receives a check valve which connects the interior of hollow packer |82 with a tube |86. 'I'his tube leads to The casing head has pump 28 which contains suitable fluid for filling and expanding the seal |82. The pump 23 operates to open check valve |85 and to close check valve |84. But when the uid pressure in casing 9| exceeds the pressure in the packer |82 caused by thepump, then the check valve |84 is forced `open by the casing pressure and the check valve |05 is forced to closure.

In like manner, the casing heads 88 and 89 contain slips for gripping and supporting the casings 92 and 93 respectively. Each casing head has a hollow packer with two check valves similarly disposed asl described for casing head 81, the radial check valves being connected to the tube |86.

` The flange |81 of a control column which may include the usual master valve, blowout preventer and mud cross rests upon the top casing head 89 ilnd is seated on the hollow packer of that casing ead.

`It will be seen that the pressure in each hollow packer of Figure 5, due to the pump may be the same, but that each packer may receive higher pressure from its casing without altering the pressure in the other seals.

In Figure 7 the sub-head is interposed between and secured by suitable bolts to the landing base and the casing head I2. The outer casing ||3 is secured to the landing base and the next casing ||4 is permanently secured by Suitable taper slips to the casing head I2. The subhead ||8 contains the hollow packer ||5 which has a dependent annular lip and likewise the subhead has lateral openings for vent pipe and for packer stem as described for Figure l. The hollow packer ||5 at its upper side bears against the bottom face of casing head ||2, the packer e'ecting seal against the casing ||3, the sub-head ||8 and the casing head ||2. Metallic packings for additional seal may be inserted between the contacting faces of the sub-head ||8 and casing head l|2 and also the sub-head and the landing base.

In the foregoing description, the term casing head is intended to apply to the elements permanentlyY secured to the casing and utilized as permanent equipment for the well. In this respect, the casing head is distinct from the drilling control column, which is a removable tool and capable of being used with a succession of wells, and moreover is distinct from the-tubing head which also is removable. An important differentiating feature is that the casing head is always below the master valve, the latter being always the bottom member of the control column and the tubing head.

I claim:

l. In a c-asing head assembly for permanently holding an outer casing and an inner casing in suspension and adapted to receive a temporarily superimposed drilling control column, through which the inner casing-is adapted to be passed, a casing head for the inner casing, a hollow infiatable packer in the casing head, the inner face of the packer having a normal relaxed diameter substantially that of the outer casing and adapted to be moved into seal with the inner casing for closing the intercasing space prior to the securing of said inner casing to the upper casing head, said packer being adapted to maintain said seal during the lowering and cementing of the inner casing, means for inflating said packer, supporting means for the inner casing above said packer and a second packer above said supporting means sealing between the casing head and the inner casing.

2. In a casing head assembly for lperxrlanently holding an outer casing and inner casing in a well, and adapted to be secured to a temporarily superimposed drilling control column, a casing head for one of the casings, a hollow packer in the casing head for sealing to the last mentioned casing, supporting means for the inner casing above said packer and a second packer above said supporting means sealing between the casing head and the inner casing, said hollow packer being normally relaxed to an inner diameter substantially equal to the inner diameter of the casing head and adapted to be moved into packing seal with said casing prior to the placing of said supporting means in said casing head.

3. In a casing head assembly as defined by claim 2, the combination therewith of means for passing fluid under pressure into said hollow packer for effecting said movement of the packer.

4. In a casing head assembly for permanently holding an outer casing and an inner casing in suspension and adapted to receive a temporarily superimposed drilling control column, through which the inner casing is adapted to be passed, a casing head for the inner casing, a movable packer in the casing head, the inner face of the packer having a normal diameter substantially that of the outer casing and adapted to be moved into seal with the inner casing for closing the intercasing space prior to the securing of said inner casing to the upper casing head, said packer being adapted to maintain said seal during the lowering and cementing of the inner casing, means for moving said packer, supporting means for the inner casing above said packer and a.

second packer above said supporting means sealing between the casing head and the inner casing.

5. A. casing head for a well casing, comprising toothed gripping means for engaging said casing to hold the same in suspension, packing means above said last named means for sealing the casing head to the casing, the casing head having appropriate surfaces for receiving and engaging both said means, a movable packer below said surfaces adapted to be moved into prior seal on 4the casing for closing the well external to the casing prior to placing the aforesaid gripping and packing means on their respective surfaces in the casing head, the movable packer being retractable to an inner diameter substantially equal to the inner diameter of the casing head.

6. In a casing head assembly as dened in claim 4 the combination therewith of means for effecting said movement of said packer.

7. A casing head for a well casing, comprising toothed gripping means for engaging said casing to hold the same in suspension, packing means above said last named means for sealing the casing head to the casing, the casing head having appropriate surfaces for receiving and engaging both said means, an inflatable packer below said surfaces adapted to be moved into prior seal on the casing for closing the well external to the casing prior to placing the aforesaid gripping and packing means on their respective surfaces in the casing head, the inflatable packer` being retractable to an inner diameter substantially equal to the inner diameter of the casing head.

8. In a casing head assembly as dened in claim '7 the combination therewith of means for inflating said packer.

9. In well equipment subject to well pressure and through which a pipe is adapted to extend; an annular hollow inflatable packing having a supplementary annular sealing member depending from the inflatable packing and extending below the inner face thereof, the inflatable packing being adapted to receive fluid under pressure for moving the packing and the supplementary member to the pipe, the said fluid pressure forcing the pacldng to seal on the pipe and the well pressure forcing the supplementary member to seal on said pipe.

10. In well equipment subject to well pressure and through which a pipe is adapted to extend; an annular hollow, inflatable sealing member adapted to be forced by internal fluid pressure within the member, to seal on the pipe, and a supplementary annular flexible sealing lip depending from said member and extending below the inner face thereof, said lip being adapted to be forced by the well pressure to seal on the pipe and to maintain said seal in the event of failure or absence of fluid pressure in said member.

FREDERIC W. HILD. 

